Toning process and product thereof.



STATES-P OFFICE" EDMUND 3.. BULLOCK, or nocnnsrrnt, NEW YORK, AssIeNon r EASTMAN KODAK comm, or ROCHESTER, NEW vonx, n conro mrro v or NEW YORK.

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full, clear, and exact description of the same,

19 4 This invention relates to a toning process TONIN PROCESS AND PROIlUC'I.

1,286,890. No Drawing.

To all-whom z'tmay concern:

Be it known that I, EDMUND R. BULLoox, a subject of the King of Great Britain, residing in Rochester, in the county of Monroe and State of New York, have invented r(i ertain new and useful Improvements in onln ereby declare the following to be a for photographic images and more particularly it concerns the toning of silver images and the improvement ofthe color of silver that imag sulfid imag My invention also embracds photographs which contain the toned image produced by my. process. Q

One object of this vinventionis to provide a process which will be satisfactorily rapid, yet easily controlled and will yield pleasing, stable, and readily duplicatedtones. A further object is to obtain a photograph containin a toned, image having'the desirable qualities and color conferrednpon it by my process. v

It is well-known to those skilled in the art es of silver sulfid, which are customarily derived by bleaching a silver image in a bath containing potassium ferricyanid and potassium bromid and subsei ently darkening the samegin a bath of; odium sulfid, often have. a 'tone which unpleasantly yellow, particularly if thjexf original silver mage be weak or low in its principal densities and if the article-size of the silver halid be very sma l in the original emulsion. It is also known that a silver image may be converted into a derived image of silver selenid-by treatment in a, bath of selenium" dissolved in sodium sulfid or sodium sulfite. The resulting tone is a dark, cold purple, which is quite unsuited for many subjects. I have discovered, however, that I can pro-\ duce an image, containing compounds of silver with'both sulfur and selenium, which hasa pleasing tone that is redder and richer than the silver sulfid image and is warmer and redder than the silver selenid image. The principles of my methobmay be employed whether I start with a primary silver image or with a silver sulfid image.

.. As a specific example of my process I shall its application to the toning of es suspended in suitable colloids atin, mounted on a paper, glass, or film base. The primary silver image is describe sllver ima Specification of Letters Patent.

Application filed June 20. 1917. Serial No: 1 75.800.

Processes and Products Thereof; and

Patented Dec. 3, 1918.

first treated in-any usual .or preferred bath or baths for the production of the secondary silver sulfid image. For instance, I may employ a bleaching bath of potassium ferricyanid and, potassium bromid followed by bath of sodium sulfid, which is the socalleli redeveloping method or I may employ the customary hypo-alum toning bath. After the sulfiding process, the print may be dried and subsequently treated, or the wet print may be immediately treated in an aqueous solution containing two-thirds of one per cent. selenium and six and two-thirds per cent. 6% of sodiumsulfite. The color of the image gradually and steadily changes, the final result being attained in a few minutes. Because of'the known stability of a silver sulfid image, this action of the selenium bath is quite remarkable and unex pected. The alteration in tone is from the yellowish hue of the sulfid to a rich reddishbroWn eflect and, since the alteration proceeds steadily, any intermediate tonemay be obtained by withdrawing the silver image from the bath'at the proper stage of the operation and washing it. This elasticity 1n manipulation also permits of the ready duplication of tone, so that whenever a satisfactory effect has been obtained, itmay be repeated and the operator need not be embarrassed by making a set of prints in which the images are of varying the casein unmodified sulfid toning. The color of the final image is due to compounds of silver, sulfur, and selenium.

The toning bath may, of course, be altered I as re ards the proportion of the several ingre ients. Sodium bisulfite may be sub? stituted, if desired,for the sodium sulfite. Furthermore, the corresponding potassium, ammonium, and magnesium salts, either singly or together, may be substituted for or combined with the sodium salts mentioned. The exact formulae of all the active agents in my toning bath are not definitely known, but it is certain that the bath ,of some acid containing sulfur and selenium several such acids being, selenosulfuric acid (H SSeO seleniumtrithionic acids (H,S,Se0,) and (H,SSe O,) and seleniumpentathionic acid (H S SeO While-it is generally not referred, on account of its odor, I may Form my toning bath by, dissolving the selenium in a solution of odium sulfid instead of sulfite.

contains salts Even where the ordinary sulfid toning methods are chiefly depended upon to modify the color of the original silver image, my process may be employed as a very useful auxiliary to save too-yellow images that would Otherwise be thrown away. The manipulation is the same as when treating the secondary sulfid image hereinabove mentioned.

Having thus- -described my invention, whatI claim and desire to secure by LetteI's Patent of the United States, is:

1. The toning 'process Which comprises converting a primary silver image into a secondary silver sulfid image and treating the latter in acid which contains selenium. a

Q. .The toning process which comprises converting a primary silver image into a secondary'image containing silver sulfid a bath containing a salt of an and treating the secondary image in a bath containing a salt of selenosulfnric acid.

3. The toning process which comprises treating a silver sulfid image in a bath containing a salt of. an acid which contains selenium.

4.. The toning process which comprises treating a silver sulfid image in a bath containing a salt of selenosulfuric acid.

5. A photograph cOmprisin'g' an image of a somewhat reddish tone including compounds of silver, sulfur, and selenium.

In testimony whereof, I have signed this specification in the presence of two witnessesthis 6th day of June, 1917-.

EDMUND .R. BULLOCK.

Witnesses:

' C.- E. MARTIN,

FRED H. GARDNER. 

